Transcript Drawings, Tables, and Graphs

Drawings, Tables, and
Graphs
Understanding when to use different
graphs and how to create them
Chapter 2 section 3 in your book
Different types of Graphic
Representations
1. Drawings – these can be used to easily represent a concept
that is difficult to explain in words.
2. Line Graphs – these can be used to show a change of one
quantity over time
3. Bar Graphs – these can be used to show the relationship
among different categories of variables
4. Circle Graphs – these can be used to show the parts of a whole
It is extremely important to choose the
right type of graph to represent your
information.
Drawings
When to use a drawing:
1) When you are wanting to show details.
2) When you are wanting to show something you can’t usually
see.
3) When you are wanting to show hidden things.
This drawing shows things you can’t
normally see and hidden things. It is a
good example of an easy to follow
drawing.
More
Drawings
The drawing below was used to show
something that is normally hidden. This
is a wiring diagram for an electronic
fireworks igniter. You can’t normally see
these things inside a firework.
The picture above is an example of a
Bohr model of an atom. It shows
something you wouldn’t normally be
able to see.
Line Graph
When to use a line graph:
1) When you are wanting to show the relationship between two
variables.
2) Each variable must be a number.
3) When you are showing the change of a quantity over time.
The graph at the left is a line graph. Notice
that both the variables along the x-axis and
the variables along the y-axis are numbers.
This graph shows that as the variable along
the x-axis increases the variable along the yaxis also increases. This is called a positive
trend or positive relationship.
How to make a line graph
1) Determine which of the variables is the independent variable
and which is the dependent variable. (If you have time as one
of the variables it is always the independent variable.)
2) Place the independent variable along the x-axis using a
reasonable scale. Remember each interval on the scale must be
the same amount.
3) Place the dependent variable on the y-axis using a reasonable
scale. Remember each interval on the scale must be the same
amount.
4) Label your axes.
5) Give your graph a good title.
6) Plot your data and connect the data points to form a line.
Let’s make a line graph
Week
1
2
3
4
5
6
7
8
Rainfall
Total (cm)
4
0
1
11
3
1
8
2
We are going to use the data table
at the left to make a simple line
graph. The table shows the
amount of rainfall at my house
over a period of 8 weeks.
Following our steps we identify the
following things:
1. Independent Variable – Time in weeks
2. Dependent Variable – Rainfall Total in
centimeters.
Continuing Line Graph
Weekly Rainfall Measurem ents Over 8 Week Period
Notice that the independent
variable (weeks) is placed on
the x-axis and the dependent
variable (rainfall) is placed on
the y-axis.
12
10
Rainfall (cm)
8
6
4
2
0
1
2
3
4
5
Weeks
6
7
8
Notice that a proper scale
was used for the graph. On
the y-axis the scale goes
from 0-12 because the data
goes from 0-11. On the x-axis
the scale includes all of the
data points.
Notice that each axis was given a label and the label included measurement units where
applicable. Also notice that the graph was given a proper title.
How are graphs graded in
this class?
Anytime you are asked to create a graph in this class it will be worth 35 points
unless you are told otherwise. That means a single graph is often worth more
than a homework assignment or quiz. You need to take your time and do good
work on graphs that are assigned. The 35 points is broken down as follows:
5 points for a good title
5 points for a correctly labeled x-axis
5 points for a correctly labeled y-axis
5 points for a reasonable scale/category labels on the x-axis
5 points for a reasonable scale on the y-axis
5 points for plotting your data accurately
5 points for presentation
Bar Graph
When to use a bar graph:
1) When
you have
categories
of
information
you want to
compare.
2) When only one
of the variables is
a number
quantity.
The graph below is a bar graph. Notice that
the dependent variable on the y-axis is in
number form, but the independent variable on
the x-axis is in category form. This is very
typical for bar graphs.
How To Make A Bar Graph
1) Determine which of the variables is the independent variable
and which is the dependent variable. (If you have time as
one of the variables it is always the independent variable.)
2) Place the independent variable along the x-axis giving each
category it’s own spot for a bar. Leave space in between the
bars.
3) Place the dependent variable on the y-axis using a
reasonable scale. Remember each interval on the scale must
be the same amount.
4) Label your axes.
5) Give your graph a good title.
6) Plot your data and draw the bars up to the proper heights to
show your data.
Let’s Make a Bar Graph
County Championships
@ OC Per Sport
Sport
# of
Champion
ships
Basketball
4
Track
1
Tennis
0
Volleyball
1
Cross
Country
9
We are going to use the data table at
the left to make a simple bar graph. The
table shows the number of county
championships won in each sport here
at Otter Creek over the last 15 years.
Following our steps we identify the
following things:
Independent Variable – Sport
Dependent Variable – Number of
County Championships
Continuing Bar Graph
County Cham pionships Won @ OC in Since 1990
10
9
# of Championships
8
7
Notice that the
independent variable
(sports) is placed on the xaxis and the dependent
variable (# of
championships) is placed
on the y-axis.
6
5
Championships
4
3
2
1
0
Basketball
Track
Tennis
Sports
Volleyball
Cross
Country
Notice that a proper scale
was used for the graph. On
the y-axis the scale goes
from 0-10 because the
data goes from 0-9. On the
x-axis the scale includes all
of the categories.
Circle Graph
When to use a circle graph:
1) When you are trying to
show parts of a whole.
2) When you are going to
convert all the number
quantities to percentages.
The graph above is a circle graph. Notice all of the numbers are
represented as percents.
How To Make A Circle
Graph
1) Determine the number of “tallies” within each category of data.
2) Determine the total number of “tallies” in the entire survey.
3) Divide the tallies in each category by the tallies in the whole to
determine the percentage for each category.
4) Multiply the percentage by 360 to determine the number of
degrees of the circle for the category.
5) Use a protractor to make each section of the circle the correct
size.
6) Label each section with a percentage and a category.
7) Give the graph a good title.
Let’s Make A Circle Graph
Students’ Favorite Core
Class
Subject
Number
Voting
For
Math
22
Science
47
Social
Studies
38
Language
Arts
19
Literature
24
Health
44
We are going to use the data table at
the left to make a circle graph. The
table shows the number of students
surveyed who voted for each of the
classes as their favorite.
The first step is to determine the total
number of students surveyed. So ….
22+47+38+19+24+44 = 194.
Now divide each piece of data by the total to
get the percentage for each category. For
example … 22 ÷ 194 = 11% The 11% is
the number we will use in the graph.
Continuing Circle Graph
The percentages for each section should
be as follows:
Math 11%
Science 24%
Social Studies 20%
Language Arts 10%
Literature 12%
Health 23%
This is a really good spot to check your work so far.
If you’ve done everything right your percentages
should total very close to 100. So…
11+24+20+10+12+23 = 100. Sometimes you
might get 99 or 101 due to rounding, but this is
obviously correct.
Now multiply each percentage by 360 to determine the
number of degrees in the circle go with that category.
For example … 11% · 360 = 39.6 degrees, which I am
going to round to 40.
Completing the Circle
Graph
The degrees for each section
should be as follows:
Math 40º
Science 86º
Social Studies 72º
Language Arts 36º
Literature 43º
Health 83º
This is another good spot to
check your math. If you’ve done
it correctly, your total should be
very close to 360º. So…
40+86+72+36+43+83 = 360.
Here again, if you’re off by 2
degrees or less it’s just due to
rounding. If it’s more than that
you’ve got a mistake somewhere.
Now use a protractor to make the graph and
you should get something like this.
Circle Graph
8th Grade Students' Favorite Classes
11%
23%
Math
Science
24%
Social Studies
Language Arts
Literature
12%
Health
10%
20%